In a wide variety of industries and professions, detectors are used to measure physical properties of interest. When one or more of these properties exceed a predetermined range, an alarm condition is signaled to one or more audible and/or visual alarms which respond by activating. For example, in a surgical operating theatre two audible and/or visual alarms can activate in response to two detected properties falling outside their predetermined ranges. In such a case, a plurality of practitioners who may be present in the theatre simultaneously to perform their respective roles are subject to both activated alarms.
During a surgical operation detectors are connected to the patient so as to measure physical properties of the patient which can include heart rate, blood oxymetry, temperature, blood pressure, ECG or other predetermined properties. It may be that different practitioners involved in the surgery are interested in monitoring different properties of the patient depending on their role in the surgery. For example, an anesthetist may be interested in monitoring the patient's heart-rate and blood pressure whereas another practitioner may only be interested in closely monitoring the quantity of a particular chemical in a patients blood.
Presently, all monitored information is available to all members of the surgical team including nursing staff even though they may not have a specific interest in monitoring a particular measured physical property to perform their duties.
Of these measured properties, it is normally the case that when they rise above or fall below a predetermined value or outside a predetermined range, an alarm condition is generated by processing electronics connected to the output of the detectors. Such alarm conditions are provided in the form of an audible and/or visual alert. For example, a visual alarm may appear or flash on a video display unit and/or an audible alarm associated with the display will activate when a measured property falls outside a predetermined range. These alarms are provided for all members of the surgical team and nursing staff and do not discriminate by providing an alarm signal to specific members of the surgical or nursing staff present in an operation. That is, all present personnel will be subject to audible and/or visual alarms when they activate.
In such situations where all members of the operating theatre are subject to those activated alarms, some personnel can either be distracted by them or alerted to an alarm condition that is not of specific interest to them. For example, the activation of an audible or visual alarm in response to a property not of specific interest to a surgeon may cause a distraction which is very undesirable.
In practice, it is common to avoid the interference and distractions caused by the activation of alarms, especially audible alarms, by turning them off or down in magnitude prior to or during a surgery. Notwithstanding that this prevents unnecessary distractions when alarm conditions occur, it defeats the purpose of employing an alarm especially when it is turned off.
It is also well known that medical practitioners and, in particular, junior practitioners are subject to relatively long hours of work. In some cases, a practitioner will only have a very specific role during a surgery, for example an anesthetist, who is only looking at particular vital signs of a patient, often on a monitor which cannot be directly seen from their preferred observation position of the patient without moving. After long periods of time it is not unknown for a practitioner to lose concentration or even fall asleep where audible or visual alarms become ineffective and they may remain unaware of the existence of an alarm condition for an undesirable period of time.
In other fields of endeavour, for example aircraft piloting, a pilot has many tasks to perform sometimes simultaneously wherein the activation of an alarm condition corresponding to a system of the aircraft may go unnoticed for some time. In the specific case of combat pilots who experience high gravitational forces, audible and/or visual signals may not be as efficiently processed by the brain than at normal G-forces and visual alarm signals can be difficult to interpret.
In the case of commercial pilots, a loss of cabin pressure of an aircraft when it is at a high altitude is communicated to a pilot by means of an audible or visual alarm which activates when the pressure falls below a predetermined level. When the cabin pressure falls slowly, it is common for a pilot to be practically unconscious when the alarms are activated. Coupled with the plethora or other audible and visual systems in an aircraft, the pilot in these situations often does not heed the alarms which may have fatal results.